FDA Reviewing Safety Data for Insulin Glargine

WASHINGTON, July 1 -- In light of four recently published studies showing a link between insulin glargine (Lantus) and cancer, the FDA announced it is reviewing safety for the drug, but urged diabetic patients not to stop treatment without consulting a physician.

Published online in Diabetologia, three of the four studies found some type of cancer-related association with the long-acting insulin analog.

However, limitations of the studies and discrepant findings call into question the validity of the association, FDA officials said in a statement.

"The duration of patient follow-up in all four studies was shorter than what is generally considered necessary to evaluate for cancer risk from drug exposure," they said.

"Further, inconsistencies in findings within and across individual studies raise concerns as to whether an association between the use of insulin glargine and cancer truly exists. Additionally, differences in patient characteristics across the treatment groups may have contributed to a finding of increased cancer risk."

All four of the studies showed some association between use of glargine or other forms of insulin and an increased risk of cancer. The association, however, emerged only in statistically adjusted or subgroup analyses. (See Mixed Message on Insulin Glargine Cancer Risk)

The American Diabetes Association, American Association for Clinical Endocrinologists, and European Association for the Study of Diabetes all issued cautionary statements about the studies.

Generally characterizing the findings as preliminary, the organizations discouraged any hasty actions by patients or clinicians.

According to the FDA statement, the agency "is currently reviewing many sources of safety data for Lantus, including these newly published observational studies, data from all completed controlled clinical trials, and information about ongoing controlled clinical trials, to better understand the risk, if any, for cancer associated with the use of Lantus.

"Discussions are also ongoing between FDA and the manufacturer of Lantus as to whether any additional studies evaluating the safety and efficacy of this drug will need to be performed."